Compact hydraulic tailgate with lift function and control method thereof

Abstract

The application belongs to the field of vehicle equipment and relates to a compact hydraulic tail door with a lifting function and a control method thereof. The tail door comprises a tail door body and a tail door rotating shaft fixedly connected to one side of the tail door body. The first piston rod is hingedly connected to the tail door rotating shaft and is further connected to the tail door rotating shaft through a helical gear mechanism, so that the tail door can drive a heavy object to vertically lift and has a turnover opening function. The tail door has the advantages of compact structure, reliable locking, stable action, strong impact resistance and non-stuck, and can be widely applied to vehicles that require the tail door to have the functions of driving a heavy object to lift and turnover opening and closing.

Description

Technical Field

[0001] This invention belongs to the field of vehicle equipment and relates to a compact hydraulic tailgate with lifting function and its control method. Background Technology

[0002] Rotatable, openable, and load-bearing tailgates are widely used in various vehicles. Currently, the drive systems for this type of tailgate mechanism are divided into hydraulic drive systems and electric drive systems.

[0003] The hydraulic drive system is generally driven by a hydraulic station to drive four oil cylinders. Two oil cylinders are used for the synchronous lifting and lowering of the tailgate, and two oil cylinders are used for the rotation opening and closing of the tailgate. Due to the large number of oil cylinders and the complex structure, the hydraulic pipeline is very inconvenient to set up. Moreover, after the tailgate is opened, the oil cylinders on both sides block the left and right movement of the equipment in the carriage.

[0004] Electric drive replaces the hydraulic cylinders of the conventional drive system with electric cylinders. Four electric cylinders drive the rotation and lifting of the tailgate. Its disadvantages are poor overload resistance, easy jamming of the mechanism, and relatively poor reliability. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a compact hydraulic tailgate with lifting function and a control method thereof, so as to solve the problem of complex structure of vehicle tailgate with lifting function.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A compact hydraulic tailgate with lifting function includes a tailgate and a compound motion cylinder. The tailgate includes a tailgate body and a tailgate pivot fixedly connected to one side of the tailgate body. The compound motion cylinder includes a rotary motion cylinder and a vertical motion cylinder connected sequentially from top to bottom. The rotary motion cylinder is a swing hydraulic cylinder and includes a rotary cylinder bottom, a rotary cylinder wall and a rotary cylinder cover arranged sequentially from top to bottom. The vertical motion cylinder is a linear motion hydraulic cylinder and includes a linear cylinder bottom, a linear cylinder wall and a linear cylinder cover arranged sequentially from top to bottom. The rotary cylinder cover and the linear cylinder bottom are arranged adjacent to each other.

[0008] The linear cylinder wall contains a piston. A first piston rod is connected to the side of the piston near the linear cylinder head, passing through the linear cylinder head. A second piston rod is connected to the end of the piston near the rotating cylinder head. The second piston rod passes through the bottom of the linear cylinder and the rotating cylinder head to insert into the output shaft located in the rotating cylinder wall. The second piston rod is splinedly connected to the output shaft.

[0009] One end of the first piston rod is hinged to the tailgate pivot to drive it to move in a linear lifting motion, and the first piston rod and the tailgate pivot are also connected by a helical gear mechanism to drive it to move in a rotating opening and closing motion.

[0010] Furthermore, it also includes a hydraulic power unit, which has a vertical control valve assembly. The linear cylinder wall has a first oil port and a second oil port for driving the piston to perform axial reciprocating motion. The vertical control valve assembly has hydraulic pipes that are respectively connected to the first oil port and the second oil port.

[0011] Furthermore, the hydraulic power unit also has a rotary control valve assembly, and the rotary cylinder wall has a third oil port and a fourth oil port for driving the output shaft to rotate. The rotary control valve assembly has hydraulic pipes connected to the third oil port and the fourth oil port respectively.

[0012] Furthermore, it also includes a top box, a first pillar box, and a second pillar box. The top box is arranged above the tailgate for installing a hydraulic power pack. The first pillar box and the second pillar box are respectively arranged on both sides of the tailgate. There are two compound motion cylinders, which are respectively installed in the first pillar box and the second pillar box to connect the two ends of the tailgate pivot.

[0013] Furthermore, the top box, the first column box, and the second column box are all hollow welded structures.

[0014] Furthermore, the helical gear mechanism includes a first helical gear fixedly sleeved on the first piston rod and a second helical gear fixedly sleeved at both ends of the tailgate pivot, wherein the first helical gear and the second helical gear mesh with each other to convert the rotational motion of the first helical gear about the vertical direction into the rotational motion of the second helical gear about the tailgate pivot.

[0015] Furthermore, the swing hydraulic cylinder is a double-helix swing hydraulic cylinder, which has a double-helix structure in the rotating cylinder wall. The double-helix structure includes an output shaft and a rotating piston. The output shaft is a hollow structure and is axially fixed in the rotating cylinder wall. Its inner wall is a spline groove, which meshes with the spline on the second piston rod. The rotating piston forms an outer helical pair by meshing its outer multi-start external helical thread with the multi-start internal helical thread of the rotating cylinder wall. Its inner multi-start internal helical thread meshes with the outer multi-start external helical thread of the output shaft to form an inner helical pair.

[0016] A control method for a compact hydraulic tailgate with lifting function, comprising the following steps:

[0017] S1. Tailgate Rotation Opening: The hydraulic power pack is started, the rotary control valve group works in the forward direction, and pressurized oil is introduced into the third oil port through the hydraulic pipeline connected to the rotary control valve group. The fourth oil port returns oil through the hydraulic pipeline connected to the rotary control valve group, so that the output shaft in the rotary motion cylinder drives the second piston rod to rotate, and drives the first piston rod to rotate. Then, through the helical gear mechanism, the tailgate rotating shaft rotates in the forward direction, and the tailgate body rotates downward to open. After it is in place, the rotary control valve group stops working.

[0018] S2. Tailgate descends vertically to its final position: With the hydraulic power pack in the activated state, after the load is pushed from the cargo compartment onto the tailgate, the vertical control valve group operates in the forward direction, supplying pressurized oil to the first oil port through the hydraulic pipeline connected to the vertical control valve group, and returning oil to the second oil port through the hydraulic pipeline connected to the vertical control valve group, so that the piston in the vertical movement cylinder drives the tailgate pivot and tailgate body to descend through the first piston rod. After reaching the final position, the vertical control valve group stops working, and the hydraulic power pack stops working.

[0019] Furthermore, it also includes the following steps:

[0020] S3. Tailgate rises to position: After the load is moved out of the tailgate to perform a ground task, when it needs to return to the cargo compartment, first move the load onto the tailgate, start the hydraulic power pack, and the vertical control valve group works in reverse. Pressure oil is introduced into the second oil port through the hydraulic pipe connected to the vertical control valve group, and oil returns through the first oil port through the hydraulic pipe connected to the vertical control valve group, so that the piston in the vertical movement cylinder drives the tailgate to rise through the first piston rod. After it reaches the position, the vertical control valve group stops working.

[0021] S4. Tailgate Rotation Closing: After the heavy object is moved into the cargo compartment, the hydraulic power pack is kept running, and the rotary control valve group works in reverse. Pressurized oil is introduced into the fourth oil port through the hydraulic pipeline connected to the rotary control valve group, and oil returns through the third oil port through the hydraulic pipeline connected to the rotary control valve group. This causes the output shaft in the rotary motion cylinder to drive the second piston rod to rotate, and then drive the first piston rod to rotate. Then, through the helical gear mechanism, the tailgate shaft rotates in the opposite direction, and the tailgate body rotates upward to close. After it reaches the closed position, the rotary control valve group stops working, the hydraulic power pack 1 stops working, and the tailgate is locked in the closed position by the hydraulic power pack.

[0022] Furthermore, once the tailgate has descended vertically to its final position, the second piston rod disengages from the output shaft, ensuring that the tailgate remains open at all times.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention provides a compact hydraulic tailgate with lifting function and its control method. Through two compound motion cylinders connected to the tailgate and a helical gear mechanism, the tailgate has the functions of rotating opening and closing, and vertical lifting with a load. The two compound motion cylinders are respectively installed in the left and right pillar boxes, making the compact hydraulic tailgate simple, compact, and functionally independent, saving installation space. Furthermore, after the tailgate is opened, the compound motion cylinders do not obstruct the left and right movement of equipment inside the vehicle, solving the problems of complex structures, inconvenient hydraulic pipeline installation, and the cylinders on both sides obstructing the left and right movement of equipment inside the vehicle after the tailgate is opened.

[0025] This invention optimizes the structure of the composite motion cylinder, making its motion logic simple and reliable, its operation smooth, and its advantages such as compact structure, reliable locking, stable action, strong impact resistance, and no jamming. It can be widely used in vehicles that require the tailgate to simultaneously drive the lifting and tilting of heavy objects.

[0026] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0028] Figure 1 This is a schematic diagram of the first structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the second structure of the present invention;

[0030] Figure 3 This is a schematic diagram of the third structure of the present invention (with mounting box);

[0031] Figure 4 This is a schematic diagram of the composite motion cylinder in this invention.

[0032] Reference numerals: 1-Hydraulic power pack, 2-First hydraulic pipe, 3-Second hydraulic pipe, 4-First compound motion cylinder, 5-Third hydraulic pipe, 6-Fourth hydraulic pipe, 7-Helical gear mechanism, 701-First helical gear, 702-Second helical gear, 8-Tailgate, 801-Tailgate body, 802-Tailgate pivot, 9-Second compound motion cylinder, 10-Fifth hydraulic pipe, 11-Sixth hydraulic pipe, 12-Seventh hydraulic pipe, 13-Eighth hydraulic pipe, 14-Top box, 15-First column box, 16-Second column box, 17-Piston, 18-First piston rod, 19-Second piston rod, a-Vertical control valve group, b-Rotary control valve group, Ⅰ-Rotary motion cylinder, Ⅱ-Vertical motion cylinder. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0034] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0035] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0036] Please see Figures 1-4This is a compact hydraulic tailgate with lifting function, including a top box 14, a first pillar box 15, a second pillar box 16, and a tailgate 8. A hydraulic power unit 1 is installed in the top box 14. A first compound motion cylinder 4 and a second compound motion cylinder 9 connected to the tailgate 8 are respectively installed in the first pillar box 15 and the second pillar box 16. The hydraulic power unit 1 is connected to the first compound motion cylinder 4 and the second compound motion cylinder 9 through hydraulic pipes to provide hydraulic power to the first compound motion cylinder 4 and the second compound motion cylinder 9. The top box 14, the first pillar box 15, and the second pillar box 16 are all hollow welded structures, and the hydraulic pipes are laid in the top box 14, the first pillar box 15, and the second pillar box 16 to simplify the structure.

[0037] Specifically, the first compound motion cylinder 4 and the second compound motion cylinder 9 have the same structure and are collectively referred to as compound motion cylinders. The compound motion cylinder includes a rotary motion cylinder I and a vertical motion cylinder II connected from top to bottom. The rotary motion cylinder I is a double helical swing hydraulic cylinder, which includes a rotary cylinder bottom, a rotary cylinder wall and a rotary cylinder cover arranged from top to bottom. The vertical motion cylinder II is a linear motion hydraulic cylinder, which includes a linear cylinder bottom, a linear cylinder wall and a linear cylinder cover arranged from top to bottom, and the rotary cylinder cover and the linear cylinder bottom are arranged adjacent to each other.

[0038] A piston 17 is provided in the linear cylinder wall, and a first linear sealing structure is provided on the piston 17 to divide the linear cylinder wall into two cavities. A second piston rod 19 is connected to one end of the piston 17 near the rotating cylinder head, and the second piston rod 19 passes through the bottom of the linear cylinder and the rotating cylinder head to be inserted into the rotating cylinder wall. A first oil port and a second oil port are provided on the linear cylinder wall on both sides of the piston 17. A first piston rod 18 is connected to the side of the piston 17 near the linear cylinder head, and a second linear sealing structure (which can be a sealing ring) is provided at the connection between the linear cylinder head and the first piston rod 18.

[0039] The rotating cylinder wall has a double helix structure, and a third oil port and a fourth oil port are respectively provided at both ends of the double helix structure to drive the double helix structure. The double helix structure includes an output shaft and a rotating piston. The output shaft is a hollow structure with a spline groove machined on its inner wall, which meshes with the spline on the second piston rod 19 and is axially fixed in the rotating cylinder wall. The rotating piston forms an outer helix pair by meshing its outer multi-start external helix thread with the multi-start internal helix thread of the rotating cylinder wall, and forms an inner helix pair by meshing its inner multi-start internal helix thread with the outer multi-start external helix thread of the output shaft. The rotating piston passes through its... The outer multi-start external helical thread is clearance-fitted with the rotating cylinder wall, and the two cavities on both sides of the rotating cylinder wall are separated by the second piston rod 19 arranged in the rotating cylinder wall and the output shaft connected to it by a spline. The third and fourth oil ports correspond to the two cavities on both sides, so that the rotating piston can move axially back and forth under the drive of the hydraulic oil injected into the third and fourth oil ports. The rotating piston moves axially under the action of the hydraulic pressure difference on both sides. Due to the meshing of the inner and outer helical splines, the output shaft is forced to rotate around its axis, which drives the second piston rod 19 connected to it by a spline to rotate. In turn, the second piston rod 19 drives the piston 17 and the first piston rod 18 to rotate. Since the driving principle of the double helix structure in the double helix oscillating hydraulic cylinder is common knowledge, this application only provides the above brief introduction and will not elaborate further.

[0040] Preferably, the first spiral sealing structure and the second spiral sealing structure are respectively installed on the second piston rod 19 at both ends of the output shaft.

[0041] Specifically, the output shaft is a hollow shaft with a spline groove on the inner wall and a multi-start external helical thread on the outer side, and is axially fixed and rotatably mounted in the rotating cylinder wall to output rotational driving force. The rotating piston is a hollow screw with multi-start helical threads on both the inner and outer sides, and the second piston rod 19 is a spline shaft to match the spline groove in the output shaft.

[0042] Specifically, the tailgate includes a tailgate body 801 and a tailgate pivot 802 fixedly connected to one side of the tailgate body 801. One end of the first piston rod 18 is hinged to the tailgate pivot 802 to drive it to move up and down. The first piston rod 18 and the tailgate pivot 802 are also connected through a helical gear mechanism 7 to drive it to rotate and open. The helical gear mechanism 7 includes a first helical gear 701 fixedly sleeved on the first piston rod 18 and a second helical gear 702 fixedly sleeved at both ends of the tailgate pivot 802. The first helical gear 701 and the second helical gear 702 mesh with each other and convert the rotational motion of the first helical gear 701 around the vertical direction into the rotational motion of the second helical gear 702 around the tailgate pivot 802. Thus, the rotation of the first piston rod 18 drives the tailgate 802 to rotate and open.

[0043] Specifically, the hydraulic power pack 1 has a vertical control valve group a and a rotary control valve group b. The vertical control valve group a is respectively connected to a third hydraulic pipe 5 and a fourth hydraulic pipe 6, which are connected to the first oil port and the second oil port of the vertical motion cylinder II in the first compound motion cylinder 5. It is also connected to a fifth hydraulic pipe 10 and a sixth hydraulic pipe 11, which are connected to the first oil port and the second oil port of the vertical motion cylinder II in the second compound motion cylinder 9. The rotary control valve group b is respectively connected to a first hydraulic pipe 2 and a second hydraulic pipe 3, which are connected to the third oil port and the fourth oil port of the rotary motion cylinder I in the first compound motion cylinder 5. It is also connected to a seventh hydraulic pipe 12 and an eighth hydraulic pipe 13, which are connected to the third oil port and the fourth oil port of the rotary motion cylinder I in the second compound motion cylinder 9.

[0044] Preferably, when the vertical motion cylinder II drives the piston 17 to move downwards, causing the tailgate 8 to descend, when the tailgate is in position, the second piston rod 19 can disengage from the output shaft in the double helix structure, but will not disengage from the rotating cylinder wall. This prevents accidental closing of the tailgate when it is in position and also limits the operating logic of the tailgate's rotation opening and closing and its lifting and lowering. That is, when the tailgate needs to be opened, the steps are as follows: first, the second piston rod 19 is driven to rotate by the rotary motion cylinder I to achieve the purpose of rotating to open the tailgate, and then the piston is driven by the vertical motion cylinder II to lower the tailgate to position. When the tailgate needs to be closed, the tailgate needs to be raised first, and then rotated to close the tailgate.

[0045] Example 1

[0046] For the tailgate of a certain heavy-duty vehicle, it needs to be rotated 90° to open first. A 200kg load is pushed onto the open tailgate, and the tailgate descends 0.8m with the load to the ground. After the load is used on the ground, it is pushed onto the tailgate, and the tailgate rises 0.8m with the load. After the load is pushed into the cargo compartment, the tailgate rotates 90° to close.

[0047] The system is configured as follows: a single compound motion cylinder has a linear stroke of 0.8m, a working torque of 600N.m, a vertical lifting capacity of 120kg (two compound motion cylinders are used, with a combined vertical lifting capacity of 240kg), and an overall length of 1.2m.

[0048] The process of opening and closing the tailgate is as follows:

[0049] 1. Tailgate Rotation Opening: The hydraulic power pack 1 is activated, and the rotation control valve group a works in the forward direction. The rotational motion cylinder I of the first compound motion cylinder 4 and the second compound motion cylinder 9 is supplied with pressurized oil through the first hydraulic pipe 2 and the eighth hydraulic pipe 13, respectively, and the oil returns through the second hydraulic pipe 3 and the seventh hydraulic pipe 12, thereby driving the second piston rod 19 to rotate and driving the first piston rod 18 to rotate. Then, through the helical gear mechanism 7, the tailgate pivot 802 is driven to rotate 90° in the forward direction, and the tailgate body 801 rotates downward to open. After it is in place, the rotation control valve group a stops working.

[0050] 2. The tailgate descends vertically into position. With the hydraulic power pack 1 in the activated state, after the heavy object is pushed from the cargo compartment onto the tailgate, the vertical control valve group b operates in the forward direction. The vertical movement cylinder II of the first compound motion cylinder 4 and the second compound motion cylinder 9 is supplied with pressurized oil through the third hydraulic pipe 5 and the sixth hydraulic pipe 11, and the oil returns through the fourth hydraulic pipe 6 and the fifth hydraulic pipe 10. The piston 17 in the first compound motion cylinder 4 and the second compound motion cylinder 9 drives the tailgate pivot 802 and the tailgate body 801 to descend through the first piston rod 19. After reaching the position, the vertical control valve group b stops working, and the hydraulic power pack 1 stops working.

[0051] 3. Tailgate rises to the correct position. After the load is moved out of the tailgate to perform a ground task, when it needs to return to the cargo compartment, first move the load onto the tailgate, then start the hydraulic power pack 1. The vertical control valve group b works in reverse. The vertical movement cylinder II of the first compound motion cylinder 4 and the second compound motion cylinder 9 is supplied with pressurized oil through the fourth hydraulic pipe 6 and the fifth hydraulic pipe 10, and the oil returns through the third hydraulic pipe 5 and the sixth hydraulic pipe 11. The piston 17 in the first compound motion cylinder 4 and the second compound motion cylinder 9 drives the tailgate to rise through the first piston rod 19. After it reaches the correct position, the vertical control valve group b stops working.

[0052] 4. Tailgate Rotation Closing. After the heavy object is moved into the cargo compartment, keep the hydraulic power pack 1 running, and the rotary control valve group a working in reverse. The rotary motion cylinder I of the first compound motion cylinder 4 and the second compound motion cylinder 9 is supplied with pressurized oil through the second hydraulic pipe 3 and the seventh hydraulic pipe 12, and the first hydraulic pipe 2 and the eighth hydraulic pipe 13 return oil. The second piston rods in the first compound motion cylinder 4 and the second compound motion cylinder 9 rotate 90° in opposite directions, driving the first piston rod 18 to rotate. Then, through the helical gear mechanism 7, the tailgate rotates upward and closes. After it reaches the closed position, the rotary control valve group a stops working, the hydraulic power pack 1 stops working, and the tailgate is locked in the closed position by the hydraulic power pack.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A compact hydraulic tailgate with lifting function, characterized in that: The device includes a tailgate and a compound motion cylinder. The tailgate includes a tailgate body and a tailgate pivot fixedly connected to one side of the tailgate body. The compound motion cylinder includes a rotary motion cylinder and a vertical motion cylinder connected sequentially from top to bottom. The rotary motion cylinder is a swing hydraulic cylinder and includes a rotary cylinder bottom, a rotary cylinder wall, and a rotary cylinder cover arranged sequentially from top to bottom. The vertical motion cylinder is a linear motion hydraulic cylinder and includes a linear cylinder bottom, a linear cylinder wall, and a linear cylinder cover arranged sequentially from top to bottom. The rotary cylinder cover and the linear cylinder bottom are arranged adjacent to each other. The linear cylinder wall contains a piston. A first piston rod is connected to the side of the piston near the linear cylinder head, passing through the linear cylinder head. A second piston rod is connected to the end of the piston near the rotating cylinder head. The second piston rod passes through the bottom of the linear cylinder and the rotating cylinder head to insert into the output shaft located in the rotating cylinder wall. The second piston rod is splinedly connected to the output shaft. One end of the first piston rod is hinged to the tailgate pivot to drive it to perform linear lifting and lowering motion, and the first piston rod and the tailgate pivot are also connected through a helical gear mechanism to drive it to perform rotational opening and closing motion. The helical gear mechanism includes a first helical gear fixedly sleeved on the first piston rod and a second helical gear fixedly sleeved at both ends of the tailgate pivot. The first helical gear and the second helical gear mesh with each other to convert the rotational motion of the first helical gear about the vertical direction into the rotational motion of the second helical gear about the tailgate pivot.

2. A compact hydraulic tailgate with lifting function according to claim 1, characterized in that: It also includes a hydraulic power unit, which has a vertical control valve assembly. The linear cylinder wall has a first oil port and a second oil port for driving the piston to perform axial reciprocating motion. The vertical control valve assembly has hydraulic pipes that are respectively connected to the first oil port and the second oil port.

3. A compact hydraulic tailgate with lifting function according to claim 2, characterized in that: The hydraulic power unit also has a rotary control valve assembly. The rotary cylinder wall has a third oil port and a fourth oil port for driving the output shaft to rotate. The rotary control valve assembly has hydraulic pipes connected to the third oil port and the fourth oil port respectively.

4. A compact hydraulic tailgate with lifting function according to claim 3, characterized in that: It also includes a top box, a first pillar box, and a second pillar box. The top box is arranged above the tailgate for mounting the hydraulic power pack. The first pillar box and the second pillar box are respectively arranged on both sides of the tailgate. There are two compound motion cylinders, which are respectively installed in the first pillar box and the second pillar box to connect the two ends of the tailgate pivot.

5. A compact hydraulic tailgate with lifting function according to claim 4, characterized in that: The top box, the first column box, and the second column box are all hollow welded structures.

6. A compact hydraulic tailgate with lifting function according to claim 4, characterized in that: The swing hydraulic cylinder is a double-helix swing hydraulic cylinder with a double-helix structure in the rotating cylinder wall. The double-helix structure includes an output shaft and a rotating piston. The output shaft is a hollow structure and is axially fixed in the rotating cylinder wall. Its inner wall is a spline groove that meshes with the spline on the second piston rod. The rotating piston forms an outer helical pair by meshing its outer multi-start external helical thread with the multi-start internal helical thread of the rotating cylinder wall. Its inner multi-start internal helical thread meshes with the outer multi-start external helical thread of the output shaft to form an inner helical pair.

7. A control method for a compact hydraulic tailgate with lifting function, characterized in that: A compact hydraulic tailgate with lifting function according to any one of claims 2-6 is provided, specifically comprising the following steps: S1. Tailgate Rotation Opening: The hydraulic power pack is started, the rotary control valve group works in the forward direction, and pressurized oil is introduced into the third oil port through the hydraulic pipeline connected to the rotary control valve group. The fourth oil port returns oil through the hydraulic pipeline connected to the rotary control valve group, so that the output shaft in the rotary motion cylinder drives the second piston rod to rotate, and drives the first piston rod to rotate. Then, through the helical gear mechanism, the tailgate rotating shaft rotates in the forward direction, and the tailgate body rotates downward to open. After it is in place, the rotary control valve group stops working. S2. Tailgate descends vertically to its final position: With the hydraulic power pack in the activated state, after the load is pushed from the cargo compartment onto the tailgate, the vertical control valve group operates in the forward direction, supplying pressurized oil to the first oil port through the hydraulic pipeline connected to the vertical control valve group, and returning oil to the second oil port through the hydraulic pipeline connected to the vertical control valve group, so that the piston in the vertical movement cylinder drives the tailgate pivot and tailgate body to descend through the first piston rod. After reaching the final position, the vertical control valve group stops working, and the hydraulic power pack stops working.

8. The control method for a compact hydraulic tailgate with lifting function according to claim 7, characterized in that: It also includes the following steps: S3. Tailgate rises to position: After the load is moved out of the tailgate to perform a ground task, when it needs to return to the cargo compartment, first move the load onto the tailgate, start the hydraulic power pack, and the vertical control valve group works in reverse. Pressure oil is introduced into the second oil port through the hydraulic pipe connected to the vertical control valve group, and oil returns through the first oil port through the hydraulic pipe connected to the vertical control valve group, so that the piston in the vertical movement cylinder drives the tailgate to rise through the first piston rod. After it reaches the position, the vertical control valve group stops working. S4. Tailgate Rotation Closing: After the heavy object is moved into the compartment, the hydraulic power pack is kept running, the rotary control valve group works in reverse, and pressurized oil is introduced into the fourth oil port through the hydraulic pipeline connected to the rotary control valve group. The third oil port returns oil through the hydraulic pipeline connected to the rotary control valve group, so that the output shaft in the rotary motion cylinder drives the second piston rod to rotate, and drives the first piston rod to rotate. Then, the tailgate shaft is driven to rotate in reverse through the helical gear mechanism, and the tailgate body rotates upward to close. After it is in place, the rotary control valve group stops working, the hydraulic power pack (1) stops working, and the tailgate is locked in the closed position by the hydraulic power pack.

9. The control method for a compact hydraulic tailgate with lifting function according to claim 7, characterized in that: Once the tailgate has descended vertically into position, the second piston rod disengages from the output shaft, ensuring that the tailgate remains open at all times.

Images